Electric discharge lamp



April 14,1942. I o. w. ATCHLEY, JR 7 ELECTRIC DISCHARGE LAMP C Filed Sept. 12, 1940 DANA W VATCHLEYI, JR.

INVENTOR.

WW M,-

A T TOENE) the press it is then in a direct line with Patented Apr. 14, 1942,

* UNITED. STATES PATENT OFFICE 1 v '7 7 Y 2,219,915: j c 4 memo mscnmaanm 'Dana W. Atchley, In, mm, asaignor to Hygrade Sylvania Corporation. Salem, liiasa, a corporation of Massachusetts Application September 12, 1940, Serial No. 356,461

' 3Claims. (Cl. 176-126) This invention relates to the stems of electric gaseous discharge lamps, and more particularly to the position at which the ventjfrom the exhaust tubing extends out of the press of the stem.

In the manufacture of electric gaseous discharge lamps with a coating of luminescent material on the inner walls thereoLjtwo problems in stem structure have proven to be diilicult of solution; one has been the blowing oil of the coating of luminescent material from the walls of the lamp due to a sudden pressure change in the lamps, and the other has been the breakin up and contamination of the alkaline earth oxide coating on the filaments due to the location of the electrode in the suction path of the vacuum pump during the exhaust process.

Accordingly,'therefore, an object of this invention is to provide a stem structure that will obviate the possibility of the luminescent coating being blown off the inner walls of the lamp. Another object is to provide a stem structure that will help reduce the contamination and' breaking-up of the alkaline earth oxide coating on the filament.

A further object is to provide a stem of a structure such that it may be readily manufactured on a regular incandescent lamp stem machine rather than requiring a special machine for gaseous discharge lamp stems.

Further objects, advantages and features will. be apparent from the specification below taken in conjunction with the accompanying drawing in which: 1

Figure l is a side elevational view of the stem stem of a fluorescent lamp be located on the sideor on the top of the press, any sudden pressure change in the lamp has often tended to cause the coating to be blown oil the walls of the lamp. Although the top of the stem press would apparently be the most logical position for the vent,

it has provento be quite disadvantageous due to the extensive exhausting process that is normally Since "the lamps are heated to a high temperature, as well as flushed several times, during the exhausting process, the many impurities drawn oif thereby are drawn across the coated filament located in the exhaust path to the exhaust tubing. Contamination of the coated electrodeis the result. Lower emission and shorter life are but two of the disadvantages that there- 'by accrue to the filament.

In view of these diificulties and disadvantages,

, I have devised a stem structure that eliminates these undesirable conditions. The vent I through the press 2, in the stem 3, is blown through the side of the press as is done in'standard incandescent lamp manufacture. On the.

lead-in wires 4 and 5, are mounted the oxide coated filament 6' and the auxiliary electrodes.

l and 8. 'To one of the lead-in wires, for example is attached the metal arm 9 of nickel, for example. To the arm 9 is attached the shield I! of nickel or some similar metal. In a stem structure of this type, any excessive pressure change in the lamp II will not blow the coating l2, of luminescent material off the walls of the lamp because the shield will be located between the vent and the walls of the lamp.

with the vent I, located on th'e'side of the press 2 instead of on the top, the oxide coated filament Sis no longer in the direct exhausting line. Thus the contamination of the oxide coatedfila- 'ment due to the several flushing operations in "the exhausting process is obviated and higher emission and longer life for the filament re suits.

With the vent located on the side of the press and the shield located between the vent and the walls of t a lamp, mercurycondensation on g the walls, due to the path through which the mercury travels into the lamp, is obviated.

Since a small quantity of mercury is introduced into the lamp after it is exhausted andtbefore it is tipped ofl, themercury often strikes the Whether the vent, through the press of the.

the lamp very often takes place. 'ation has a very undesirable effect on the ap- "walls of the'lamp when it drops down from-the Since the lamp is still hot vent in the stem. from the exhaust oven when the mercury is introduced, mercury condensation on the walls of pearance of the lamp'and should be" avoided. The shield in my invention deflects the mercury awayfrom the walls of the lamp asit comes employed; When the vent is located on top of out of the vent in the stem and directs it downward to theopposite end of the lamp.

What I claim is:

ljIn a stem for electric gaseous discharge This discolcr- 7 lamps having a coating of luminescent material therein and a vent in the side of the stem: lead v wires-projecting through the top 01 said stem.

an arm attached to and extending from one of V said lead wires, and a shield attached to the end of said arm and located near and in line with said .vent, said' shield protecting the luminescent .coating on the walls of the lainp fron the vent discharge."

2. In 'a stem fee-e ema amt-m v lamps having a coating of luminescent material therein, said stem'having a vent in the'yside prising: a tubular envelope; a coating of fluores fromone of said lead-in wires, anda shield attached to the end of said armin line with and spaced from said vent, said shield protecting the luminescent coating on the walls of thelamp from the vent discharge.' 1

3. An electric gaseous discharge lamp comcent material on the inside of saidtubular envelope;;a stem-ior closing anend of said envelope.

thereof: lead-in wires proiecting through the top a of said stem, an arm attachedto and. extendin mm W. new, a, 

